Method of making color separation negatives



P. GLAFKIDES Filed May 12, 1939 METHOD OF MAKING COLOR SEIKARATION NEGATIVES Aug. 25, 1942.

NEGATIVE POSITIVE NEGATIVE POJITIVE INVENTOR.

ff g .1 ATTORNEY.

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.keep their several Patented Aug. 25, 1942 UNITED STATES PATENT AAoFFicE l l'ME'rnon or mxglgn sErAimfrroN Pierre Glafkides, Brooklyn, N. Y. Application May 12, 1939, Serial No. 273,167

Y1 Claim.

This invention relates to the art of color photography and relates more particularly to an improved method of making a. plurality of color separation negatives from a single negative element comprising a plurality of emulsion layers superimposed on a single base.

The present application constitutes a conand passes both red and green light. The second and third emulsions as well as the sepdescribed more in tinuation-in-part of my copendmg application Ser. No. 221,480, iiled July 27, 1938. g

The principal object of the present invention is the provision of an improved method for making color separation negatives on separate bases from a negative material of the type described in my co-pending application, such material comprising a plurality of photographic emulsions superimposed on a base, said emulsion layers being separated from each other by intermediate insulating layers.

Another object of the present invention is the provision of an improved method of developing the three emulsions, one at a time, so as to operations separate and without any coloring process. The invention further provides a method of individually removing or attacking each of the several deposited layers, one at a time, without acting on the other layers. Also, the present invention includes the method of selectively printing each emulsion after it has been developed, without exposing the remaining emulsions. Y

'I'he method which constitutes the present invention is carried out with a composite negative material which has a base composed of the usual material and three emulsions separated by two thin lms of varnish. 'I'he light sensitive emulsion deposited on the emulsion sensitive to all three colors but designed to receive the red image only. A thin iilm of varnish, insoluble in any developing agent but easily soluble -in a solvent or capable of being attacked by a chemical reagent, is deposited on the iirst emulsion, the iilm covering the surface of the emulsion. A second emulsion is deposited on the-rst lm of varnish which is sensitive to the green and blue colors, designed to record the green only. A second film of varnish similar to the.iirst is deposited on the second film. The third emulsion is deposited on the second varnish lm and is .sensitized for the blue color v only and is designed to record that color.

The rst film of varnish, between the red and green sensitive emulsions, is colored red so that only-red light passes through the same. The second lln of varnish, between the green and base is a panchromatic blue sensitive emulsions, is colored a light yellow arating iilms are of such character, as will be detail hereinafter, as to perxrit the major portion of the light to pass therethrough and thus present clear images to the ilrst and second emulsions.

The exposure is made as follows: The iilm is placed in the camera, emulsion side towards the lens as usual, and the exposure is4 made. The third emulsion .records the blue because it is sensitive only to the blue rays. The remainder of the light passes through the second varnish, and because of its color only the red and green rays are transmitted. The second emulsion is sensitized to the green and blue-rays but receives only red and green light; hencevl the green rays are recorded. The first film of varnish passes only the red light in the image and it exposes the rst emulsion which is sensitive to all the rays. Y

' As an alternate method, the iiltering actions of the two varnish films may be incorporated in the emulsions themselves or a combination method may be used.

After the laminated negative has been placed in the camera and exposed tothe image, it is then' developed in an ordinary developer, iixed, washed and allowed to dry. Inasmuch as the internal emulsions are protected by the insulating-layers,fonly the external or top emulsion is developed in black and white in this rst operation.

The laminated negative cannot, however, be exposed to light as yet, since the rst and second emulsions are still undeveloped. In the event, however,l that the insulating layers are dyed as filters, and if the negative material is backed by an anti-halation coating impervious to light, the

laminated negative material may afterward be which phenomena might occur by virtue of print-I the red latent image remains.

ing through the emulsions. In contact printing, on the other hand, the use of infra-red light tends to minimize diffusion effects, and when a perfect contact is obtained between the negative and the copying material, diffusion is reduced to a minimum.

The print thus obtained is either developed normally or is developed and reversed, and accordingly gives a duplicate of one of the color separation negatives.

l In a normally coated rst duplicate is the record. If, however,

negative material, the duplicate of the blue violet the base is coated reversely and exposed with its back toward the lens, the first duplicate is that of the red record. In this instance, the printing of this rst copy may be made with red light instead of infra-red light inasmuch as the remaining emulsions are not, then, sensitive to red.

The third gelatine layer which bears the rst image to be printed is then removed in a manner which will hereafter be described in detail, in order to vpermit the second emulsion to be developed.

The second varnish fum must be removed or attacked. Any solution which acts on the varnish but not the gelatine emulsion may be used. This leaves the second emulsion film exposed and it may be developed, washed, flxed and printed in the same manner` as the third emulsion.

The second emulsion and the rst varnish film are removed in the same manner as described above, after which the rst emulsion bearing This may be developed and fixed in the ordinary manner, after which it may be used as a color separation vnega.- tive and printed on a positive lm or paper with ordinary light since no undeveloped emulsion remains. The three separation prints are used in any of the usual positive processes.

For the purpose of better illustrating the method employed in carrying out the present invention, the accompanying drawing shows a number of sectional views of the laminated material.

In the drawing:

Fig. l shows a negative base provided. with three superimposed emulsion layers which are separated from each other by insulating layers; f

Fig. 2 shows a modified type of negative material wherein two bases are provided;

Figs. 3, 4 and 5 illustrate the several steps in the printing operation from the exposed laminated negative material.

As previously stated, material comprises a single base and a plurality of layers of emulsionthereon. In Fig. 1 the base III may be made from plate glass, cellulose nitrate, cellulose acetate or other suitable materials. n one side of the base a plurality of layers of emulsion II,. I2 and I3, respectively, are formed, such layers being separated from each other by insulating layers Il and I5. The emulsion II in contact with thebase is panchromatic and sensitive to red,vgreen and bluelight although only the red light reaches this emulsion.

The second layer chromatic and is sensitive to green and blue, and the third emulsion I3 is sensitive to blue violet only and is accordingly an ordinary emulsion.

Such a negative is to be exposed, through the medium 'of a camera, with the emulsion side of emulsion I2 is ortho.

the improved negative towards the lens. If, however, the layer in contact with the base is sensitive to blue violet only: and the top layer is arpanchromatc emulsion, the material is then exposed with the base towards the lens.

The insulating layers I4 and I5 are used to separate the emulsion layers from each other. The texture of the insulating layer may be either non-porous or porous, and the procedure of ap' plication will vary accordingly. In the event that the insulating layer has a -porous texture,

. the pores must besuiciently small as to stop the molecules of all chemical agents, other than water, in aqueous solution. Such an insulating layer is similar to a semi-permeable membrane presenting osmotic pressure, and can be coinpared to a net, the meshes of which permit molecules of predetermined size only to pass therethrough. This porous insulating agent must also be of such character as to becapable of having the pores enlarged, by the use of a suitable chemical reagent, in order to permit larger molecules to pass therethrough.

After the negative material Ihas been exposed and the third emulsion layer-developed and the positive print made therefrom, the gelatine layer constituting this third emulsion is now removed in order to allow the second emulsion to be developed. This gelatine layer may be dissolved in an aqueous solution of one of the following chemicals:

Sodium hypochlorite Sodium hydroxide Sulfochromic acid l lSodium iodide concentrated Sodium bromide concentrated Lithium chloride concentrated In this connection it has been found that sodium hypochlorite solution gives the best results. In view oi the particular composition of the emulsion layer, sodium may be substituted for any other alkaline metal. The concentration of the bath and the time of the immersion will,

., of course, vary according to the degree of softfreely therethrough. To this end solvents are employed, but not in suiiicient quantities to dissolve the layer. A chemical agent ymay be employed for this purpose, which agent tends to slow down or counteract the dissolving action.

In the case ofcellulose Vnitrate layers, the negative material may be immersed in a mixture containing two parts by volume of amyl acetate and one part by volume of ether. This same negative material is then allowed to dry and, on the varnish so treated, a thin layer of a solution of methyl alcohol and acetone in equal parts by volume is applied to such surface. No part of the semi-permeable layer is removed by dissolution in this operation.

It must be noted that the pores of the insulating layer are enlarged after the external emulsion layer has been totally removed. 'I'his same insulating layer has become an external protective layer and is not an intermediate layer any more.'

' I3. Inasmuch as Furthermore, said semi-permeable layer is not rendered permeable to treatment liquids but to chemical agents only, since it was already permeable to water before processing. If the insulating varnish has an impermeable, non-porous or uniform texture, it is totally dissolved with a solvent of such a type as not to cause injury to the emulsion lying immediately th'erebeneath. For instance, in the case of a resin; caustic soda in aqueous solution may be used. In the event that there is a tendency for the` reagent to dissolve or attack allowed to remain in contact with the solvent by its emulsion side only, or, in other words, to be floated on the solution.

In reproducing the colored picture from the negative, a plurality of separate color lseparation negatives may be formed, or a colored positive consisting of a base and a plurality vof superimposed colored images may be printed directly from the negative. Only the latter method is ilthe base, the negative rmaterial is lustrated in the drawing, and in Fig. 3 the combined laminated negative and positive material are shown together with the exterior surface or the emulsion I3 of the negative material in meet- `ing engagement with the positive emulsion |9 l on the printing material I8. The outer or third emulsion layer |3 has been developed in the manner previously described, and there is accordingly formed in this layer an image designated as the ilrst and second emulsions are not as yet developed, and accordingly should not be subjected to ordinary light, infra-red light is used for the purpose of printing the images lfrom this third emulsion layer onto the positive emulsion I9. The positive and negative elements occupy the position shown when contact printing is employed. Somewhat better results are obtained, however, by projection printing.

'Ihe image I3 in the layer I3 is, of course, not in color, and when a direct colored positive is made the positive emulsion I9 on the printing material is dyed to produce the desired color for such image, which, in the case of the printing emulsion I9, is yellow. When this positive emulsion 9 is developed, an image |9' will be visible thereon corresponding to the blue record on the negative. The negative image layer I3 is now removed in the manner previously described, and

Y' the second insulating layer |5 is also removed\ and the second emulsion layer developed, thereby producing th'e image I2 in such layer, such image corresponding to the green record. The positive material is now given a second positive emulsion 2|, the image of which in the instance shown will be dyed magenta, and such layer on the positive material is placed in meeting engagement with the external surface of the second emulsion layer I2 having the image I2' thereon. Infra-red light is also used to print this image I2 on the positive emulsion 2| superimposed on the base I8. Thus, the image 2|' is printed on this second layer on the positive material, and the second emulsion layer and its adjacent insulating layer is then removed and the process continued. The positive material is then given a third sensitized layer 25, and for the purpose of printing the image from the first emulsion layer II white light may be used. I

In the event th'at separate color separation negatives are to be prepared from the laminated exposed negative. th'e positive material |8 having the sensitized .positive V4emulsion I9 thereon,

shown in Fig. 3, may, when developed, be used for producing the rst color separation negative, and `after the third emulsion layer I3 and its adjacent insulating layer I5 have been removed and the image on the' veloped, this image may be printed again on positive material having a single positive emulsion thereon, and a second color separation negative made from this second positive. The repeated for the third layer of emulsion, although after the second emulsion layer and its adjacent insulating layer have been. removed, the cle-` veloped image on the first emulsion layer and the supporting base I0 may be used as a negative.

A modification in the construction of the foregoing laminated negative material is shown yin Fig. 2 and comprises a base 30 having superimposed emulsion layers 3| and 32 thereon, such layers being separated by an insulating layer 33. A third emulsion layer 34 is positioned upon a second base 35. The external faces of the emulsion layers 32 and 34 are placed in face to face engagement, and the two lms placed together direction of the arrow, and the iirst emulsion layer 3| is desirably for recording the blue record. The second emulsion layer 32 preferably records the green, and .the third emulsion layer 34, which' is in physical contact with the second emulsion layer, is for recording the red.

It will be appreciated, of course, that the positions of the several emulsions may be reversed,

thereby having the ordinary emulsion at 34 and the emulsion for the red record at 3|.

Through the specification the term ."emulsion is deemed to mean either a imposed layers of emulsion having similar chromatic characteristics.

be appreciated. Likewise, an insulating layer o similar material, and in some instances one of such layers may consist of a clear varnish and the second layer may be colored to act as a filter for the light. Also, the filtering material may be incorporated within the emulsion layers rather than in the insulating layers. The termfimpermeable layer as used in the appended claim may be dened as a layer impermeable both to water and to molecules of chemical agents in aqueous solution, and th'e term semi-permeable layer may be dened as a layer having the character of a semi-permeable membrane, i. e. impermeable to molecules of chemical agents but permeable to water at all times. Such layer has a nely porous structure. A gelatine (or other colloid) layer is considered a permeable layer water and chemical agents.

What I claim'is:

'I'he method of enlarging the pores of a semipermeable cellulose nitrate layer of a photographic element, which consists in rst treating th'e surface thereof with a mixture `of approximately two parts by volume of amyl acetate and one part by volume of ether and then treating such surface with a mixture of approximately equal parts by volumenof methyl alcohol and acetone. l

PIERRE GLAFKIIIDES.`

second, ,emulsion layer destepvmay be It may be substituted by any other kind of photo-sensitive, material, as will 

